It is known that a golf club consists of a shaft, most commonly made of metal, and a head connected to the shaft by means of an upward extension of the shaft usually referred to as the "neck". The head and shaft are generally assembled by inserting the shaft into the neck and bonding it in place, in particular through the use of adhesive. The golf club head forms the striking member proper. In order for it to strike correctly the head should rest substantially flat on the ground when the shaft of the club forms a specific angle with respect to the ground, this angle being the angle called the "lie" of the shaft. It can easily be seen that the angle of "lie" of a golf club varies in relation to the player and essentially depends on the player's grip and height. In the case of a club such as a putter three main values of the angle of lie are generally defined, corresponding to three positions of the player, i.e., three positions of the shaft, namely, a median position and two extreme positions obtained by displacing the axis of the shaft to either side of the median position by about 2.degree.. Attempts have therefore been made, in particular in the case of precision clubs like putters, to make it possible to alter the angle of lie easily in such a way as it can be adjusted to the player's grip.
Various solutions have been proposed to solve this problem, in particular by deforming the neck after a golf club has been assembled. In the case of traditional putters, i.e., putters in which the upper part of the head supporting the neck has a certain flexibility with respect to the head, the deformation is applied in this upper part and is progressively distributed over the length thereof. Conversely, in some putters the upper part of the head has a structure which makes it rigid so that it cannot deform. In this case, the bending force is taken up by the neck exclusively. In order to retain the deformation applied to it in the course of bending, to adjust the angle of lie, the latter must have mechanical properties such that the stresses applied to it are in excess of its elastic limit, so that the material does not resume its original position after deformation, and below its fracture limit, so as to avoid breaking the neck of the golf club.
The head of a golf club is constructed of a material which is selected on the basis of mechanical stresses which are not necessarily the same as those required for the construction of the neck. As a result, the forces applied to the latter in the course of the operation of adjusting the angle of lie are not within the range of the aforementioned mechanical stresses. Thus, if the material forming the head is not sufficiently rigid, the neck will tend to resume its initial position after bending, and if, on the contrary, it is too hard there will be a risk of it breaking during the bending operation. Furthermore, generally for aesthetic reasons, golf club heads are normally provided in their upper part with a connecting portion which is generally conical and tapers from bottom to top in order to provide the connection to the shaft of the club. This connecting part has the disadvantage of interfering with the inclination of the club shaft when it is desired to alter the angle of lie of the latter. In addition, the connecting part forms a protuberance which gives rise to complications during moulding, and may sometimes result in defective products.
In traditional club heads in which the neck is integral with the head, being an extension on a single piece, there are generally defects in concentricity, and therefore defects in alignment, between the shaft and the neck, and these defects may be corrected or at least masked by a conventional part called a ferrule.